Simplify the following expression: $r = \dfrac{7z}{5} + \dfrac{3z}{5}$
Explanation: Since the expressions have the same denominator we simply combine the numerators: $r = \dfrac{7z + 3z}{5}$ Combine like terms: $r = \dfrac{10z}{5}$ Simplify by dividing numerator and denominator by 5: $r = \dfrac{2z}{1}$ $r = 2z$